Because of the need to be placed inside a house, size of furniture must be adjusted to the space of the house. Since residential space is generally narrow in Japan, this need is considerably strong. In order to meet this need, conventional ready-made furniture provides a plurality of types each having a different size so that consumers can choose a type which may fit to the layout or size of their own residential space. However, even though a plurality of types each having a fixed size are provided, range of choice is limited, and thus the needs of customers are not sufficiently met.
As the method to design an article, many methods such as three-dimensional CAD, etc. are known. By these methods, a product with desired specification can be designed by first displaying the entire three-dimensional design of the product of its original standard specification on a PC screen, and then inputting alteration of the specification. Inventor of the present invention once proposed a design system of custom-made furniture, which stores the standard specification data of furniture in a computer, and alters the standard specification data to accord to customers' request (patent document 1).